Purpose
To develop a segmental tibial bone defect model for tissue engineering
studies in veterinary orthopedics using single locking compression plate
(LCP) fixation and cast immobilization.
Methods
A 3-cm bone defect was created in the right tibia of 18 adult Suffolk sheep.
A 10-hole, 4.5-mm LCP was applied to the dorsomedial aspect of the bone.
Four locking screws were inserted into the proximal and three into the
distal bone fragment. Operated limbs were immobilized with casts. Animals
were submitted to stall rest, but were allowed to bear weight on the
operated limb. During the recovery period, animals were checked daily for
physiological parameters, behavior and lameness. Follow-up radiographs were
taken monthly.
Results
Surgical procedures and postoperative recovery were uneventful. Animals
adapted quickly to casts and were able to bear weight on the operated limb
with no signs of discomfort or distress. No clinical or radiographic
complications were detected over a 90-day follow-up period.
Conclusions
Surgical creation of tibial segmental bone defects followed by fixation with
single LCP and cast immobilization was deemed a feasible and appropriate
model for veterinary orthopedic research in tissue engineering.
Fracture management poses a great challenge to large animal practitioners. Osteosynthesis alone is often insufficient to provide satisfactory outcomes in large animals; therefore, several research efforts have been made to investigate and develop bone substitutes capable of promoting bone regeneration. Chitosan-collagenhydroxyapatite composites constitute a promising alternative given their similar composition to bone. Six Santa Inês ewes were submitted to the creation of experimental 7mm wide unicortical defects on the dorsomedial aspect of the proximal III/IV metacarpal bone diaphysis. Limbs were randomly selected for treatment with chitosan-collagen-hydroxyapatite composite or to serve as untreated controls. Biopsy fragments were collected from the bone/new bone or the bone/biomaterial interface (control and treated defects respectively) within 60 days of surgery; composite biocompatibility was assessed using light and scanning electron microscopy. Histomorphometric analysis under light microscopy revealed greater percentage of new bone tissue in control compared to treated defects (80% and 63.5% respectively; P<0.05). No scar tissue formation, foreign body or chronic inflammatory reactions were observed. Scanning electron microscopy revealed invasion of the composite by new bone tissue. The chitosan-collagen-hydroxyapatite composite studied is biocompatible with bone and shows osteoconductive properties in sheep.
Strangulating obstruction of the small intestine by anomalous mesenteric bands is an uncommon cause of colic in horses.The most commonly reported bands are mesodiverticular bands that are embryological remnants of the vitelline arteries. Despite the congenital nature of the anomaly, a wide age range of horses can be affected. This report describes a case of small intestinal strangulating obstruction caused by an unusual, anomalous congenital band attached to the ileocaecal fold in a yearling colt. Information including case background, history, clinical, laboratory, surgical and pathological findings is described.
O compósito à base de hidroxiapatita, quitosana e nanotubo de carbono foi desenvolvido com o intuito de auxiliar na consolidação óssea. Estudos anteriores sugerem que a combinação de substitutos ósseos e células-tronco mesenquimais (CTM) podem auxiliar a potencializar e promover a regeneração óssea. No presente estudo, o biomaterial foi desenvolvido e a viabilidade e a citotoxicidade de células Vero (ATCC CCL-81) e CTM obtidas de medula óssea provenientes de ovinos utilizando ensaios metil-tiazol-tetrazólio, MTT e iodeto de propídeo (PI) foram avaliadas em diferentes concentrações de extrato desse compósito. O compósito demonstrou ausência de citotoxicidade com comportamento semelhante ao grupo controle. Amostras com 50% e 10% de concentração de extrato do compósito mostraram resultados maiores comparados ao grupo controle (ensaio MTT). Esses resultados também sugerem que a presença do biomaterial pode ser utilizada em associação a CTM. Assim, esse estudo conclui que o compósito apresentado de hidroxiapatita, quitosana e nanotubo de cabono não foi considerado citotóxico e pode ser utilizado em teste in vivo.
Mineralization of the anatomical structures involved in the limb movement of horses has been reported to induce lameness and interfere with athletic performance. A 4-year-old jumping horse in sport activity was reported at Veterinary Hospital of University of São Paulo, with mild lameness and a mineralized oblique distal sesamoidean ligament (ODSL) of the left forelimb, revealed by a purchase radiographic and ultrasound examination. Mineralization is more common in tendons than ligaments. This report calls for attention to these structures when performing image exams, even in mild lameness. Long-term favorable follow-up by ultrasonographic and radiographic examination showed that the severe ligament injury in this case did not decrease the athletic activity until the present day.
Background: Bone substitutes have been developed to assist bone regeneration in orthopedic surgeries. Mesenchymal stem cells can be added to these biomaterials to enhance bone regeneration. This study aimed to evaluate the biocompatibility and osteoconduction of a carbon nanotube, chitosan, and hydroxyapatite nanocomposite (CNCHN) that had either been enriched or not enriched with sheep bone marrow mesenchymal stem cells (BM-MSCs) in rats. Methods: A total of sixty rats were divided into groups, and an implant with or without BM-MSCs was performed subcutaneously in 20 animals (euthanized after 7 and 30 days), comparing them to 10 control animals, and in the calvaria of 20 animals (euthanized after 20 and 60 days), comparing to with 10 control animals. Subcutaneous and calvaria histologies were performed after euthanasia. Results: The subcutaneous tissue showed that CNCHN did not prompt an exacerbated inflammatory response or signs of necrosis. The histomorphological analysis by the calvaria score of the rats showed that the control group had lower scores at 20 and 60 days for bone neoformation, relative to the CNCHN groups, which showed no significant statistical differences, suggesting that the nanocomposite assisted in the regenerative process of defects in the calvaria, but with no repair potentiation when using BM-MSCs. Conclusion: CNCHN has biocompatibility and osteoconductive potential, showing promising results in bone defects.
Biomateriais tem diversas indicações como auxiliares no processo de reparação óssea, além de terem função de substituto ósseo em perdas extensas. Diversas são as vantagens de sua utilização, como por exemplo, auxílio na osteocondutividade, estímulo de neovascularização, potencial antimicrobiano, entre outros. Falhas ósseas foram realizadas nas tíbias de seis ovinos da raça Santa Inês e preenchidas com biomaterial à base de quitosana, colágeno e hidroxiapatita. Um membro foi considerado controle e outro membro tratado segundo estudo randomizado. Foram realizadas avaliações termográficas e por ultrassonografia Power Doppler em todos os animais do estudo, semanalmente, nos dias D0, D7, D14, D21, D28, D35, D42 e D56. Não houve diferenças significativas com relação à temperatura mínima, máxima e média entre os grupos com biomaterial e controle nas imagens termográficas. Houveram variações com relação ao tempo dentro de ambos os grupos. Com relação à presença de vasos na ultrassonografia Power Doppler não houve diferenças estatísticas entre os grupos, exceto no dia 21 (P=0,031). Dentro das possibilidades de avaliação que os exames de imagem fornecem, a termografia e a ultrassonografia Power Doppler mostraram-se ferramentas não invasivas de avaliação pós-operatória de processo inflamatório e neovascularização, sendo realizadas semanalmente, permitindo acompanhamento fidedigno e detalhado ao longo do experimento, sem gerar desconforto ou estresse aos animais. Não houve indícios de complicações relacionadas ao biomaterial.
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